This invention relates to apparatus for radiating ultraviolet light. More particularly this invention relates to a novel ultraviolet light applicator device including a means for safely powering same.
In various dental procedures, it has been found desirable to apply to the surface of the teeth a polymeric sealing or adhesive material. For instance, certain types of polymeric material has been found to be effective as an adhesive for attaching various structures to the teeth as may be necessary in orthodonture or as a sealant for the tooth surface. The resins employed in such procedures are of a type which harden (cure) by being exposed to ultraviolet (UV) light. One such sealant or adhesive composition is described in U.S. Pat. No. 3,712,984 as the reaction product of bisphynel A and glycidyl methacrylate combined with about 20% benzoin methylether just before the resin is to be applied. To cure the resin it is then exposed to ultraviolet light for periods of up to 2 minutes depending on the extent and nature of the ultraviolet (UV) light supplied.
The aforesaid U.S. Pat. No. 3,712,984 issued Jan. 23, 1973, discloses apparatus apparently suitable for applying UV light in such procedures to harden and cure the adhesive in the patients mouth. As stated in the aforesaid patent, one specific requirement for a UV light applicator is the necessity of exposing the sealant to the light in the relatively confined area of the patient's mouth adjacent to the teeth. Of equal, if not greater importance, is the requirement that the patient not be exposed to any harmful effects by use of the UV light. Since it is known that certain ranges of frequency wavelengths of UV light are harmful to human tissue, minimal exposure, even to relatively safe UV wavelengths, is therefore, necessary. Secondly such light is necessarily generated by electrical apparatus which thereby also may generate excessive heat or present an electrical shock hazard to both the patient and the dentist. Finally such a UV light applicator should be small enough and convenient to use by the dentist and to fit inside the patient's mouth. As a practical matter, it must also be economical to purchase, maintain and use for this specific purpose.
As previously mentioned such an applicator is disclosed in the aforementioned U.S. Pat. No. 3,712,984 which shows a gunlike hand-held housing in which the UV light is generated and a bent tubular optical rod for transmitting and applying the UV light inside the patient's mouth. The apparatus shown in the aforesaid patent generates excessive heat including light in undesirable and dangerous frequencies of UV radiation. Therefore, the apparatus must be cooled, have a temperature sensitive cutoff switch, and a UV light filter in connection with its operation, all in the hand-held portion thereof. As such, the applicator disclosed in the aforementioned patent is quite complicated and cumbersome. Thus the filter is employed to eliminate undesirable UV short wavelength light under 320 nanometers (nm) as well as 90% wavelengths of the light in the 500 to 600 nm band. To provide for patient safety, the light transmitting quartz rod is employed to direct the filtered UV light to the desired area inside the patient's mouth. While such a device is presently in commercial use and is the only other such dental UV light applicator of which we are aware, it is quite clearly complicated and cumbersome together with other associated disadvantages. Another U.S. Pat. No. 3,868,513 issued Feb. 25, 1975 for a UV Radiation Projector is illustrative of another complex version of a UV applicator.